Inhomogeneity of phase transformations β → ω and β → α in the quenched cold-rolled alloy Zr-20%Nb

The inhomogeneous character of phase transformations in the quenched cold-rolled alloy Zr - 20%Nb was investigated using new X-ray diffractometric procedures based on a position sensitive detector. It was shown that the distribution of strain hardening in β-grains with different orientations controls the development of phase transformation β→α and β→ω in the rolled alloy. Derivative phases inherit the substructure inhomogenity of the β-phase, i.e. their grains are most dispersive and/or have the most distorted crystalline lattice in texture minima, where both phase transformations develop primarily. To explain the obtained X-ray texture data a mechanism was suggested involving local formation of quasi-amorphous boundary interlayers by cold rolling and their crystallization by annealing.